Electromagnetic vibrator

ABSTRACT

An electromagnetic vibrator in the form of a dual mass vibratory system. The vibrator includes a first mass in the form of a base having a central recess and including at least two extensions extending substantially parallel to the vibration axis of the vibrator. A magnetic system is positioned within the recess. The vibrator includes further at least one leaf spring packet and rigid thread means associated with the extensions for fastening ends of the at least one leaf spring packet. Means are provided for rigidly coupling the central portion of the at least one leaf spring packet to a second mass.

I United States Patent 1 1 1 1 3,764,834

Brosch et al. Oct. 9, 1973 [5 ELECTROMAGNETIC VIBRATOR 2,694,156 11/1954Cerminara 310/29 x [75] Inventors: Leo Brosch,Stetten; Gerd Fechner,FOREIGN PATENTS OR APPLICATIONS gP fi h g g g ii f g, 520,680 5/1940Great Britain 310 29 IIC elmt1ngen,a o ermany Primary Examiner-D. F.Duggan [73] Ass1gnee: Transformation Union Aktiengesell- Atmmey (3eorgeH Spencer et 1 schaft, Stuttgart-Bad Cannstatt, Germany 57 ABSTRACT [22]Filed: 1971 An electromagnetic vibrator in the form of a dual [21] Appl.No.: 189,233 mass vibratory system. The vibrator includes a first massin the form of a base having a central recess and including at least twoextensions extending substan- [30] Foreign Application Pnonty Datatially parallel to the vibration axis of the vibrator. A Oct. 15, 1970Germany P 20 50 647.2 magnetic system is positioned within the recess. hvibrator includes further at least one leaf spring v s v s e a I s 1 e sv s 1 e s 1 s s 1 s n [5 1 [EL k tensions for fastening ends of the atleast one leaf Fleld of Search 17, 29, p g packet MeanS are provided forp i g the central portion of the at least one leaf spring [56]References cued packet to a second mass.

UNITED STATES PATENTS 8 Claim 2 Drawin Fi ures 3,167,670 1/1965 Spurlin310 29 g 5 3,155,853 ll/l964 Spurlin et al. 310/29 PATENTEU BET 9 1975FIG./

ELECTROMAGNETIC VIBRATOR BACKGROUND OF THE INVENTION This inventionrelates to an electromagnetic vibrator in the form of a dual massvibratory system. In particular, the invention relates to anelectromagnetic vibrator in'the form of a dual mass vibratory systemusing leaf springs as spring elements.

It has already been proposed to clamp leaf spring packets which serve asthe vibratory element in an electromagnetic vibrator, contrary to theprevious custom, rigidly and particularly force-transmittingly inlongitudinal direction so that when the springs are vibrating, theirtensile strength is stressed more than their bending strength whichconstitutes a substantial increase in the magnitude of the resettingforce.

This increased stress in the axial direction of the springs must, ofcourse, also be absorbed by the fastening portions and thespring-supporting frame. Elasticity and/or resiliency in these portionsof the vibrator lower the calculated spring constant which permits thedevelopment of undesirable natural frequencies and reduce the attainableuseful output.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide an electromagnetic vibrator in the form of a dual mass vibratorsystem having an improved, high useful output.

Itis another object of the present invention to provide anelectromagnetic vibrator in the form of a dual mass vibrator system inwhich a mass in the form of a base is provided with extensions whichextend substantially parallel to the vibration axis of the vibrator andinclude rigid thread means for fastening ends of a leaf spring packet.

It is a further object of the present invention to provide anelectromagnetic vibrator in the form of a dual mass vibrator system inwhich a magnetic system is positioned within a recess formed within oneof the dual masses.

It is an additional object of the present invention to provide anelectromagnetic vibrator in the form of a dual mass vibrator systemwhich is substantially free of undesirable resonances.

It is yet another object of the present invention to provide anelectromagnetic vibrator in the form of a dual mass vibrator system fromwhich heat removal is substantially improved.

It is yet a further object of the present invention to provide anelectromagnetic vibrator in the form of a dual mass system which issimple and inexpensive to fabricate.

The abovementioned and additional objects are accomplished by anelectromagnetic vibrator in the form of a dual mass vibratory systemincluding a first mass in the form of a base having a central recess,the base including at least two extensions extending substantiallyparallel to the vibratory axis of the vibrator. A magnetic system ispositioned within the recess. The vibrator includes additionally a leafspring packet and rigid thread means associated with the two extensionsfor fastening ends of the leaf spring packet. A second mass is rigidlycoupled by conventional means to the central portion of the leaf springpacket.

The first mass is preferably the operating mass and is designed as abase, more or less in the form of a plate, having a central recess tohold the magnetic system.

The extensions, which extend substantially parallel to the vibrationaxis of the vibrator, contain at least two rigid threads which serve tofasten the ends of a leaf spring packet. The central portion of the leafspring packet is rigidly coupled with the second mass.

With this particular design of the base, a high rigidity is obtained sothat leaf spring mounts attached to the two outer edges can beconsidered to be sufficiently rigid.

A further improvement is realized if, according to a further inventiveidea, the magnetic system is designed as a C-core and mounted in therecess of the base. Particularly when this magnetic system is rigidlyconnected with the base by means of a cast resin and the recess is fullyfilled with a solid mass, extraordinary rigidity is obtained which caneven be augmented further by reinforcing ribs leading to the extensionsfor fastening the leaf spring packet.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of anelectromagnetic vibrator in the form of a dual mass vibratory systemaccording to the present invention.

FIG. 2 is a sectional view of a second embodiment of an electromagneticvibratory system according to the present invention which has a highervibrating frequency than the embodiment illustrated in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring in detail to FIG. 1,the electromagnetic vibrator includes a base 10, more or less in theform of a plate, which includes a first mass illustrated as a workingmass in accordance with a preferred embodiment.

The base 10 is provided on the right and left with rigid cast extensions11 which are stiffened by ribs 12. Each of the extensions 11 is providedwith a threaded bore, generally designated by the numeral 13.

A recess 14 is provided in the base 10 for accommodating a magneticsystem which comprises a C-shaped core 15 and a winding 16. Asillustrated, the C-shaped core 15 and the winding 16 are encased in castresin.

A leaf spring packet, including a plurality of leaf springs 17 separatedfrom one another by specific, highly stressable intermediate layers 18,is fixed at its ends to the extensions 11 by high-tensile bolts 19(expansion screws) which extend into the threaded bores 13. Theintermediate layers 18 may desirably have inwardly prepressed contactingedges. The intermediate layers 18 may be of conventional material.

The central portion of the leaf spring packet including the leaf springs17 and the intermediate layers 18, is connected by conventional means toa second mass 20 which is separated from the C-shaped core 15 by an airgap and acts as an armature.

Center clamping of the leaf spring packet including the leaf springs 17and the intermediate layers 18 is effected by bolts 21 which extendthrough a free side member 22. If desired for frequency tuningadditional weights, generally designated by the numeral 23, may be fixedto the side member 22 by bolts 24 which extend through a plate 25, theplate 25 forming part of the additional weights.

The base 10 is provided with an indent or groove 26 extending around asurface in its periphery. A protective hood 27 having a sealof profiledmaterial 28 is positioned over the structure, the profiled material 28being seated in the indent or groove 26. The protective hood is providedwith step-like indentations 29 for seating annular screws 30 which areprovided to hold the protective hood 27 in place. As illustrated, theannular screws 30 are provided with free ends 31 of O-shape which may beused for transportation purposes.

During vibration strong tensile forces are exerted on the outer springmounts, which forces are absorbed by the force-transmitting clampingarrangement, rigid housing including the extensions 11, the high-tensilebolts 19 (expansion screws) and the specific, highly stressableintermediate layers 18. Movement within the mount of the leaf springpacket is virtually impossible so that wearing from friction andundesirable damping from these causes are for practical purposeseliminated.

The embodiment of the invention illustrated in FIG. 2 of the drawings isconstructed and operates similarly to the embodiment of the inventionshown in FIG. 1 of the drawings. The prime numerals used in FIG. 2designate parts corresponding to parts designated by correspondingnumerals used in FIG. 1 without a prime sign. Thus, it is not necessaryto describe FIG. 2 of the drawing in detail.

The electromagnetic vibrator in the form of a dual masssystem asillustrated in FIG. 2 is provided. with an air gap between a C-core anda second mass which is somewhat less than the air gap between the C-.core 15 and mass 20 shown in FIG. 1 Additionally, the leaf spring packetcomposed of a plurality of leaf springs 17 and intermediate layers 18'is not as thick as the corresponding leaf spring packet shown in FIG. 1.As a consequence of these differences (smaller air gap and less totalspring tension), the electromagnetic vibrator shown in FIG. 2 operatesat a higher frequency (50 Hz) than the frequency Hz) at which thevibrator shown in FIG. 1 operates.

While no additional weights, corresponding to weights 23, areillustrated in FIG. 2 of the drawing, it is to be appreciated that suchweights could be placed between the plate 25' and the side member 22' ifdesired for frequency tuning.

With the configuration of the vibrator according to the presentinvention not only the desired rigidity is obtained for the clampingpoints of the leaf springs but also a simplification and reduction ofcost of the fabrication is effected. In addition, due to the closeposition and connection of the magnetic system with the part in theoperating side of the electromagnetic vibrator which serves as the base,the heat removal is substantially improved since the entire vibratoroperating side acts as a reflecting surface, on the one hand, and, onthe other hand, heat can be conducted via the vibrator mounting feet toa connecting block of the conveyor trough or the like. This permitssubstantially better utilization of the active material.

It will be understood that the above description of the presentinvention is susceptible to various modifications, changes andadaptations, and the same are intended to be comprehended within themeaning and range of equivalents of the appended claims.

We claim:

1. In an electromagnetic vibrator having a vibrating axis andconstructed in the form of a dual mass vibratory system the improvementcomprising in combination: a first mass in the form of a base having acentral recess, said base including at least two stiff, rigid extensionsextending substantially parallel to the vibration axis of the vibratorand having respective threaded bores therein; radially extendingexternal ribs stiffening said extensions, resulting in a progressivespring rate; a magnetic system within said recess; at least one leafspring packet composed of a plurality of individual springs and thin,relatively narrow, highly stressable intermediate layers having inwardlyprepressed contacting edges, said layers being disposed between saidsprings; respective rigid threaded, high-tensile expansion screw boltspositioned in said respective bores of said extensions and extendingthrough respective end portions of said at least one leaf spring packetfor rigidly and securely fastening ends of said at least one leaf springpacket against tension forces; a second mass; and means for rigidlycoupling said second mass to the central portion of said at least oneleaf spring packet whereby the elastic resetting force for therealization of the vibrating movement is obtained by utilization of thesuperposition of the deflecting force on the pulling force due to thelongitudinal expansion of the leaf springs forming the at least one leafspring packet.

2. The apparatus as defined in claim 1 wherein the magnetic systemcomprises a C-shaped core.

3. The apparatus as defined in claim 1 wherein the magnetic system isfixed in said recess by cast resin means.

4. The apparatus as defined in claim 2 wherein the C-core is fixed insaid recess by cast resin means.

5. The apparatus as defined in claim 1 including a U- shaped memberembracing the at least one spring first mass is the working means of thevibrator.

* 3 i I i UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PatentNo. ,834 Dated October 9th, 1973 l-( Leo Brosch, Gerd Fechner and EduardReichert It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

In the heading of the patent, line 5, change "Transformation to-Transformatoren--.

Signed and sealed this 9th day of April 1971;.

(SEAL) Attest:

EDWARD M.FI.J3TCHER,JR. G. MARSHALL DANN Attesting Officer Commissionerof Patents FORM F'O-1050 uscoMM-oc wan-Pen fi UTS. GOVERNMENT PRINTINGOFFICE: "I! 0-365-334.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,764,834 Dated October 9th, 1973 lnventofls) Leo' Brosch, Gerd Fechnerand Eduard Reichert It is certified that error appears in theabove-identified patent and that said Letters Patentare hereby correctedas shown below:

In the heading of the patent, line 5, change Transformation" to--Transfor n 1-atoren--.

Signed and sealed this 9th day of April 1971;.

(SEAL) Attest:

EDWARD PLFLETCHEEJR. C. MARSHALL DANN v Attesting Officer Commissionerof Patents USCOMM'DC 60376-P69 FORM F'O-105O (10-69) V Q U.S. GOVERNMENTPRINT NG OFFICE ll! 0-!66-331. A

1. In an electromagnetic vibrator having a vibrating axis andconstructed in the form of a dual mass vibratory system the improvementcomprising in combination: a first mass in the form of a base having acentral recess, said base including at least two stiff, rigid extensionsextending substantially parallel to the vibration axis of the vibratorand having respective threaded bores therein; radially extendingexternal ribs stiffening said extensions, resulting in a progressivespring rate; a magnetic system within said recess; at least one leafspring packet composed of a plurality of individual springs and thin,relatively narrow, highly stressable intermediate layers having inwardlyprepressed contacting edges, said layers being disposed between saidsprings; respective rigid threaded, high-tensile expansion screw boltspositioned in said respective bores of said extensions and extendingthrough respective end portions of said at least one leaf spring packetfor rigidly and securely fastening ends of said at least one leaf springpacket against tension forces; a seconD mass; and means for rigidlycoupling said second mass to the central portion of said at least oneleaf spring packet whereby the elastic resetting force for therealization of the vibrating movement is obtained by utilization of thesuperposition of the deflecting force on the pulling force due to thelongitudinal expansion of the leaf springs forming the at least one leafspring packet.
 2. The apparatus as defined in claim 1 wherein themagnetic system comprises a C-shaped core.
 3. The apparatus as definedin claim 1 wherein the magnetic system is fixed in said recess by castresin means.
 4. The apparatus as defined in claim 2 wherein the C-coreis fixed in said recess by cast resin means.
 5. The apparatus as definedin claim 1 including a U-shaped member embracing the at least one springpacket on the side thereof remote from the base.
 6. The apparatus asdefined in claim 1 including a protective hood means for enclosingactive components, said hood means including stepped regions at whichfastening bolts and annular eyes for transporting purposes are provided.7. The apparatus as defined in claim 6 wherein the protective hood meansis seated on outer edge portions of said base by means of a profiledseal and a recess formed in the outer edge portions of the base.
 8. Theapparatus as defined in claim 1 wherein the first mass is the workingmeans of the vibrator.